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> 제 목 Theoretical and experimental study of novel quantum dot lasers

> 강 사 Jungho Kim

> 소 속

> Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, USA.

> 시 간 2005년 10월 31일 월요일 오전 11시

> 장 소 신공학관 301동 1112호

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> Abstract

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> Semiconductor quantum dot (QD) lasershave drawn much attention due to expected performance improvement over quantum well (QW) lasers such as lower threshold current density, higher differential gain, and lower linewidth enhancement factor (LEF). However, poor carrier capture and relaxation efficiency of the self-assembled QDs limit the performance of QD lasers. Recently, two new structures of QD lasers are proposed and implemented to overcome the problems in conventional QD lasers. One is a tunneling injection scheme, and the other is a p-type modulation doping scheme.

> In this talk, a theoretical and experimental study of these new structures of QD lasers is presented. In a p-doped InAs/InGaAs/GaAs QD laser operating near 1.3 m, we investigate the effect of p-type doping on the LEF by matching measured modal gain and refractive index changespectra with a theoretical model. In a tunneling injection InP/GaInP/InAlGaP QD laser emitting red light (650 nm), we focus on a particulargain narrowing behavior, which can be explained by a proposed polarization-dependent photon-mediated carrier re-distribution.

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> 강사이력

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> Jungho Kim received the B.S. and M.S. degrees in electrical engineering from Seoul National University, Seoul, Korea, in 1998 and 2000, respectively. He is currently working toward the Ph.D. degree in the Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana.

> From 2000 and 2001, he was a full-time researcherat the Electrical Engineering and Science Research Institute, Seoul, Korea, where he was engaged in the development of bidirectional optical transmission systems, polarization-mode dispersion compensators, and fiber-optic sensor systems based on fiber Bragg gratings. He was also involved in analyzing the resonance radiation trapping in a plasma display panel using Monte Carlo simulation. He is currently working on theoretical modeling and experimental characterization of quantum-cascade and quantum-dot lasers. He also contributes to the theoretical investigation of the electromagnetically induced transparency in quantum-dot and quantum-well structures. His research interest in optoelectronic devices covers a dilute-N, GaN-based and organic material systems.

> Mr. Kim won a distinguished M. S. thesis award from the School of Electrical Engineering at Seoul National University, in 2000, and a silver prize in the 6th Human Tech Thesis Contest sponsored by Samsung Electronicsfor excellence in research.